Pressure seated electrical connections in a flexible hydrophone array



Feb. 10, 1970 w. L. ANGELOFF 3,495,210

PRESSURE SEATED ELECTRICAL CONNECTIONS IN A FLEXIBLE HYDROPHQNE ARRAY Filed April 4, 1968 INVENTOR. WESLEY L. ANGELOFF ttes 3,495,210 PRESSURE SEATED ELECTRICAL CONNECTIONS IN A FLEXIBLE HYDROPHONE ARRAY Wesley L. Angelotf, San Diego, Calif., assignor to the United States of America as represented by the Secretary of the Navy Filed Apr. 4, 1968, Ser. No. 718,686 Int. Cl. H04b 13/00; H02g /08 US. Cl. 340-9 1 Claim ABSTRACT OF THE DISCLOSURE The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND Hydrophones and transmitting transducers must be lowered considerable distance over the side of a moving or stationary boat. The hydrophone and/or transducer must be in a long rope-like in-line array which can be towed astern of a fast moving boat and yet can be handled and stowed aboard without damage to the transducer elements. Although piezoelectric crystals or ceramics are light in weight and are eflicient for transducing signals, the elements are fragile and are vulnerable to breakage. Further, the problems are formidable of making electrical connection to the plated electrodes on the inside and outside surfaces of the cylinders.

An object of this invention is to provide an improved flexible in-line hydrophone array.

More specific objects of this invention are to provide a long flexible hydrophone array which can easily be handled aboard the carrying boat without danger of that:- turing the sensitive elements.

A still further object of this invention is to provide a hydrophone array with novel means for making electrical connection to each of the electrodes of each of the pieZoelectric elements.

SUMMARY The active elements of the array of this invention comprises short cylinders of electrically polarized ceramic material to the inside and outside surfaces of which is applied a foil or film-like electrode of good noncorrosive metal such as silver or nickel. A first tubular webbing of loosely interwoven strands of wire extend along the interior of the end-to-end cylinders and is expanded into contact with inside electrodes. Preferably the cylinders are spaced along the webbing by insulating cylinders. A second flexible tubular webbing of loosely Woven strands of wire is telescoped over the array and is permitted to shrink into firm pressure contact with the outside electrode of each of the cylinders of the array.

Other objects and features of this invention will become apparent to those skilled in the art by referring to the preferred embodiment described in the following specification and shown in the accompanying drawing in which the single figure shows in perspective a section of one preferred embodiment of this invention.

The type of array contemplated here has the general outside appearance of a garden hose which may be many feet long and one inch in diameter and which is quite flexible and can be coiled. More specifically, the elements of the hydrophone array are shown as cylinders 10 in the drawing. The cylinders may be of barium titanate or lead zirconate and are plated exteriorly and interiorly with a non-corrosive good conducting metal such as silver or nickel. For purposes of illustration the thickness of the electrodes, shown at 10:: and 10b, is most exaggerated. The ceramics are fired with a direct current biasing potential applied to the electrodes to polarize the ceramic, the direction of polarization in this case being such that the diameter of the cylinder changes in response to an applied signal. The cylinders are relatively short so as to minimize breaking strain when the array is coiled upon a fairly small reel.

The active elements 10 are spaced desired distances apart by non-conducting spacer elements 12. The spacers 12 are preferably of the inside and outside diameters of the active elements 10 are are of flexible material such as plastic or rubber.

In manufacture, all of the cylinders 10 and 12 are telescoped over the tubular webbing 14. The webbing 14 may, conveniently, be of the type used for shielding well known in the shielded cable art. The tubular webbing comprises interleaved spirals of fine wire, spiraled helix fashion about the tubing in opposite directions and being woven, simply, in an in and out or over and under weave. At the cross over points of the in and out weave, the strands are approximately at right angles so that tension lengthwise of the webbing will tend to shrink the diameter of the webbing. When the lengthwise tension is released, the webbing tends to spring back and exert considerable outward radial pressure against the inner metal electrode 10a. Conveniently, longitudinal tension can easily be applied to facilitate the telescoping of the cylinders 10 and 12 over the webbing.

It is preferred that the rubber tube 18 be telescoped inside of webbing 14 and that the two elements 14 and 18 be stretched during the foregoing operation of telescoping elements 10 and 12 over the webbing. The tube 18 can increase the pressure of the webbing 14 against the ceramic elements, as well as insulate the webbing from cable 22 and any conductors that may be threaded through the tube.

Next, with all the cylinders 10 and 12 pressed firmly end to end, the tubular webbing 16, with its exterior rubber tube 20, is slid over the assembled cylinders. To facilitate this operation the webbing 16 is of inside diameter slightly greater than the ouside diameters of the cyinders. When the webbing 16 is in place it can be stretched to contract the inside diameter of the webbing 16 into contact with the outside electrodes, 106, of the active elements 10.

It will now appear that good electrical contact has been made with each plated electrode of each of the active elements by the two webbings 16 and 18 without the troublesome and expensive operations of soldered wire connections.

To remove excessive tensions on the array during towing or handling, it is preferred that a steel cable 22 be telescoped interiorly of the rubber tube 18 and attached mechanically to the aft end of the array. Conveniently, the annular space between the tube 18 and the cable 22 may receive electrical conductors for completing circuits to desired elements of other arrays. Electrical connections, not shown, are made between the webbings, 14 and 16, and receiver or transmitter equipment.

A hydrophone or transducer array constructed according to this invention is mechanically strong in tension, is

3 l inexpensive to manufacture, and can be handled without a first flexible rubber-like tube inside the first menfear of breakage of the active ceramic elements. tioned tubular webbing and of an outside diameter to What is claimed is: press said first webbing outwardly, and 1. A transducer array comprising: a second flexible rubber-like tube outside the second a first and a second flexible tubular webbing of loosely interwoven spiraled strands of wire,

a plurality of cylinders of piezoelectric material with film-like metal electrodes applied to the interior and References Cited exterior surfaces, respectively, of each of said cylin- UNITED STATES PATENTS ders, said cylinders being disposed end-to-end,

mentionad tubular webbing and of an inside diametea to press said second webbing inwardly.

the first of said flexible tubular webbings extending 10 2,732,536 1/1956 M1116? 340-10X along the interior of said end-to-end cylinders, and 2,864,073 12/1958 Harms 34010X pressing in good electrical contact with the inside 2,923,916 2/1960 Woodworth 340-10X electrode of each of said cylinders, 3,027,540 3/1962 Howatt 340 10 the second of said flexible tubular webbings extending 15 3,067,401 12/1962 Rhociles 17484-3 along and around the exterior of said end-to-end 3,286,227 11/1966 Aldnch 340*10X cylinders, and pressing in good electrical contact with the outside electrode of each of said cylinders, RODNEY TT, JR., Prunary Examiner cylinders of insulating material between said cylinders B, L, RIBANDO, Assistant Examiner of piezoelectric material, 20 all said cylinders being of like inside and outside diameters to permit said tubular webbings, respectively, to lay in firm contact with the entire surface of each electrode, 

